function alphanew = getAlfFromLd(Ld, q, Ma, S, g, mass)
    alpha = 8*pi/180;
    L0 =  getL(alpha, q, S, g, mass, Ma);
    L1 =  getL(alpha + pi/180, q, S, g, mass, Ma);
    alphanew = alpha + (Ld - L0)/(L1 - L0);
    i = 0;
    while(abs(alphanew - alpha) > 0.5*pi/180 && i < 9)
        alpha  = upperLowerLimit(alphanew, 0, 20*pi/180);
        L0 =  getL(alpha, q, S, g, mass, Ma);
        L1 =  getL(alpha + pi/180, q, S, g, mass, Ma);
        alphanew = alpha + (Ld - L0)/(L1 - L0);
        i = i + 1;
    end
end
function L = getL(alpha, q, S, g, mass, Ma)
    L = q*S*(0.4172+19.41*alpha+10.17*alpha^2-Ma*(0.1004+0.7536*alpha))/mass/g;
end